[PATCH] rtc: small documentation update

Rtc driver documentation update

* Mention the max-user-freq control file.
* Add missing header in example code.

Signed-off-by: Jean Delvare <khali@linux-fr.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Jean Delvare 2006-06-25 05:48:23 -07:00 committed by Linus Torvalds
parent 8e12ecc2b5
commit 9be05b57bd

View File

@ -44,8 +44,10 @@ normal timer interrupt, which is 100Hz.
Programming and/or enabling interrupt frequencies greater than 64Hz is
only allowed by root. This is perhaps a bit conservative, but we don't want
an evil user generating lots of IRQs on a slow 386sx-16, where it might have
a negative impact on performance. Note that the interrupt handler is only
a few lines of code to minimize any possibility of this effect.
a negative impact on performance. This 64Hz limit can be changed by writing
a different value to /proc/sys/dev/rtc/max-user-freq. Note that the
interrupt handler is only a few lines of code to minimize any possibility
of this effect.
Also, if the kernel time is synchronized with an external source, the
kernel will write the time back to the CMOS clock every 11 minutes. In
@ -81,6 +83,7 @@ that will be using this driver.
*/
#include <stdio.h>
#include <stdlib.h>
#include <linux/rtc.h>
#include <sys/ioctl.h>
#include <sys/time.h>